Circuit breaker having arc extinguishing medium of granulated insulating material which includes a lubricant to decrease friction between elements thereof



Oct. 19, 1965 H. GREBER 3,213,251 CIRCUIT BREAKER HAVING ARCEXTINGUISHING MEDIUM OF GRANULATED INSULATING MATERIAL WHICH INCLUDES ALUBRICANT TO DECREASE FRICTION BETWEEN ELEMENTS THEREOF Filed Feb. 5,1962 INVENTOR.

United States Patent 3,213 251 CIRCUIT BREAKER HAV ING ARC EXTINGUISH-lNG MEDIUM 0F GRANULATED INSULATING MATERIAL WHICH INCLUDES A LUEEEEANTT0 DECREASE ERECTION BETWEEN ELEMENTS THEREOF Henry Greber, 225 W. 80thSt., Apt. 8D, New York, N.Y. Filed Feb. 5, 1962, Ser. No. 171,098 1Claim. (Cl. 200-149) The object of this is to provide a circuit breakerof considerable interrupting capacity whose container is filled withgranulated, or pulverized, non-flamable insulating material. The use ofsmall pellets, sand or powder of glass porcelain, steatite and similarsolid materials as fillers of circuit breakers opens new possibilitiesfor the latter, by making them explosion-proof, which is particularlyimportant in their application in locations with fire and explosionhazards.

The single figure shows a schematic sectional view of the breaker withsolid filler. Numeral 1 designates the movable contact made of alongitudinally corrugated tube provided with point 2. The longitudinalgrooves of the corrugation 20 are shown on the surface of tube 1.Movable contact 1 fits into the steady contact 3, made of a tube withholes 4 all along it. End of tube 3 has the form of a funnel 5. Fingercontact 1 fits also into another contact 6, made of a tube with twofunnel-shaped ends 7 and 8. All contacts are mounted Within aninsulating cylinder 9, which is partly filled With granulated orpowderized insulating material 10. On the end of finger contact 1 isplaced strain insulator 11, through which a mechanism (not shown) movessaid finger contact 1 in and out of contact 3. The source of voltage 12is connected by means of conductor 13 with steady contact 6, and bymeans of conductor 14 with useful resistance 15, which represents theenergy consuming device, and is linked through conductor 16 with steadycontact 3. Locknuts 1'7 and 18 and stud 19 serve for connection ofconductor 16 to steady contact 3.

In operation of this circuit breaker, as soon as the mobile contact 1 isseparated from the steady one 3, the space between them isinstantaneously filled with the solid filler 10, and a possible arebetween the separated contacts is extinguished or prevented. The finerthe solid filler, the smaller is the gap between the separated contactswhich is immediately filled with the granulated or powderized insulatingmaterial. There exists an obvious possibility of using a combination ofthe above named fillers, pellets and powder, or balls and smallgranules. Thus the interstices between the pellets and balls arecompletely filled with sand-shaped or powderized insulating material.Talcum powder, silicon liquid can be used for lubrication, in order todecrease friction between the insulating balls, pellets, and particlesof insulating sand and powder, and also the friction between theseparticles and the metallic contacts. To achieve a breaking up of the arcspace into component ones, the pellets or granules can contain cores ofmetallic powder or such of semiconductors, for example of graphite.

As mentioned the present circuit breaker does away with the danger ofexplosions, always present in oil filled circuit breakers. At the sametime the circuit breaker with solid filler has a greater short circuitinterrupting capacity than the corresponding air circuit breaker. Inaddition to this the solid filler dissipates better heat from thecontacts at their passage by rated current. The present solid fillerscan be used to facilitate current interruption in such devices asstarters, contactors, rotary switches, relay contacts, collectors ofelectrical machines, for eX- ample for a DC. machine with verticalcollector immersed in a solid insulating medium of granulatedconsistency. The housing of knife switches with flicker blades can befilled with such medium. In the present circuit breaker the volume ofits solid, granulated filler can be much smaller than that of acorresponding insulating liquid. Therefore smaller breakers of highercurrent interrupting capacity than the ones now available can be builtaccording to the present invention. Many modifications and variations ofthis circuit breaker can be made in the spirit and within the scope ofthe following claim.

I claim:

A circuit breaker comprising, in combination; an enclosure substantiallyfilled with a granulated insulating material; a tubular steady contactmeans having a flared end, said tubular steady contact means beingmounted in said enclosure and completely covered by said granulatedinsulating material; a movable finger contact means consisting of apointed longitudinally corrugated tube mounted for cooperativeengagement and disengagement with said tubular steady contact meansthrough its flared end, to open and close a circuit; holes in the wallof said tubular steady contact means to allow displacement of thegranulated insulating material during engagement of the movable fingercontact means with the tubular steady contact means; and said granulatedinsulating material including a lubricant consisting of talcum powder todecrease friction between the granules of the granulated insulatingmaterial and between the granules and the movable and steady contactmeans.

References Cited by the Examiner UNITED STATES PATENTS 766,187 8/04Hellmund 200--151 813,546 2/06 Fellenberg 20012O 2,377,689 6/45 Hyde200- FOREIGN PATENTS 446,121 6/27 Germany.

KATHLEEN H. CLAFFY, Primary Examiner.

ROBERT K. SCHAEFER, Exan'zl'ner.

